Audio out over USB could bring docks similar to the iPod/iPhone however the main issue I see here is port placement. Sometimes its on the bottom sometimes its on the side sometimes its back to front (Looking at your HTC)
USB audio output support allows hardware vendors to build hardware such as audio docks that interface with Android devices. This functionality is also exposed with the Android Open Accessory Development Kit (ADK) to give all developers the chance to create their own hardware
If you haven’t checked out what’s to come with Jelly Bean, Have a good read on the Android Developers site.